Mechanism of percussive action



Dec. 5, 1967 L. P. KozLov MECHANISM OF PERCUSSIVE ACTION Filed April 30, 1965 v w R u Y United States Patent ce 3,356,165 MECHANISM F PERCUSSIVE ACTION Leonid Pavlovich Kozlov, Poselok 2, No. 10, Apt. 19,

Moscovskaya Oblast, Solnechnogorsky Raion, Povarovo, USSR.

Filed Apr. 30, 1965, Ser. No. 452,130 13 Claims. (Cl. 173-124) ABSTRACT OF THE DKSCLSURE A mechanism of percussive action preferably for drilling machines is provided with means constituting a working chamber lilled with liquid and being under pressure of a resilient element, such as gas separated from the liquid by movable partition. The part of a hammer block (head) is located in the chamber and a clutching means connected with drive and periodically engaging the hammer block under the action of the liquid in the chamber to stop by means of the drive, the hammer block being moved by the liquid for an impact after disengaging the clutching means.

The present invention relates to those mechanisms of percussive action in which the hammer block periodically interacts with the drive through a piston clutch.

Known percussive-action mechanisms of the aforementioned type are characterized by low power in general and low energy of single blow in particular. The impact loads arising in the operation of known mechanisms, and more specically, on clutching the hammer block, are transmitted to the drive, which affects considerably the service life of the above mechanisms.

Known percussive-action mechanisms, such as the pneumatic types, those with a flexible or cam hammer block coupling, or with a pneumatic hammer block coupling (compression-vacuum ones) also have a number of serious disadvantages.

Thus,V pneumatic percussive mechanisms are of low eiliciency due to compressed air losses when compressing the air and delivering it via mains. Percussive mechanisms with a lexible or cam hammer block coupling in the majority of cases also fail to meet the necessary requirements.

The excessive impact loads arising in the course of operation of known mechanisms have an adverse effect upon their durability, with the forward and backward waves spreading beyond the hammer block at the moment of impact. The mechanisms are also characterized by low power and low single stroke energy.

The known percussive mechanisms with a pneumatic coupling, i.e., with an air cushion between the hammer block and the workpiece connected with the drive are superior to those with a flexible or cam coupling between the hammer block and the drive in that they permit-eliminating impact loads thus having a longer service life.

However, in pneumatic coupling mechanisms, the hammer block moves, when on forward stroke, under the action of a continuously compressed air cushion, the air pressure increasing by dozens of times and the temperature by hundreds of times, which is a considerable disadvantage. On the back stroke, the gas of the air cushion is ratified, with the hammer block being acted upon only by the pressure-difference value between the atmosphere and the cushion, a value always below l kg./cm.2, which strictly limits the number of blows, the stroke of the blow piece, the plunging of its mass, as well as reduces the power of single blow.

The object of this invention is to eliminate the abovementioned disadvantages.

3,356,165 Patented Dec. 5, 1967 Another and more particular object of this invention is to design such a mechanism ot percussive action as should develop the maximum single blow power at a low power consumption, and make it possible to Widely regulate power during operation. It is still another object of this invention to eliminate the dynamic loads acting upon the drive while clutching the blow piece.

The present mechanism of percussive action incorporates a hammer block housed in a body, reciprocating and periodically interacting on the back stroke with a drive through a clutch. According to the invention, the body portion which houses the travelling clutch together with that part (head) of the hammer block with which said clutch reciprocates, also serves as a liquid-lled working chamber. The working chamber is connected to an additional chamber carrying a resilient element, such as gas, with such element serving to create constant pressure through an elastic or movable partition (separating the liquid from the elastic element), and the constant pressure acting upon the liquid in the working chamber which transmits kinetic energy to the hammer block, thus actuating said clutch. The drive, with which the hammer block interacts, is connected to the clutch through a crank-and-rod transmission. The part (head) of the hammer block which is housed in the working chamber and which interacts with the clutch, has a cross-section exceeding that of the hammer block head facing the working tool.

The clutch is a hollow cylinder rigidly fixed to the end of the connecting rod. The diameter of the hammer block head corresponds to the inside diameter of the cylinder. The cylinder carries a back-pressure valve serving to let the liquid through the cylinder when the hammer block head enters its interior. The hammer block retreats together with the cylinder, and its head is acted upon by the liquid pressure resulting from the backward stroke of the working tool.

The hammer block is provided with channels in its body, which, on full back stroke, connect the interior of the clutch cylinder with the working chamber for insuring the disengagement of the hammer block from the clutch. The additional chamber carrying a resilient element is a vessel and the movable partition separating the resilient element from the liquid of the working chamber is a piston. The vessel carrying the resilient element may be located either outside, or inside the body of the mechanism and the drive of the mechanism is kinematically connected to the clutch through a cam transmission.

The vessel with the resilient element may be a movable cylinder rigidly connected to the clutch and periodically interacting with the cam transmission. In the front portion of the body is installed an axially movable sleeve which constitutes one of the Walls of the Working chamber and the sleeve serves as a guide for the hammer block and absorbs the reilected shock waves.

The working chamber is connected to a liquid feeder of rather low output, with the liquid circulating inside the chamber and escaping through a special pipeline carrying a suction valve to adjust pressure inside said chamber.

The cross-sectional area of the connecting rod should be approximately twice less than that of the part of the hammer block facing the working tool.

Further objects and advantages of the invention will become more readily apparent to persons skilled in the art from the ensuing detailed specification and annexed drawings, and in which drawings:

FIGURE 1 is a view partly in elevation and partly in cross section of a percussive mechanism having a gascarrying vessel located outside of the body thereof, and

FIGURE 2 is a fragmentary view partly in elevation and partly in cross section of the mechanism having a gascarrying vessel located within the body.

The mechanism of the percussive action shown in FIG. 1 comprises a cylindrical body 1 housing a hammer block 2 adapted to execute a reciprocal motion, and a clutch 3. The internal cavity of body 1 formed by a floating sleeve 4 and by the body walls serves as a working chamber 5 filled with liquid, such as oil. Working chamber 5 is in permanent connection with cavity 6 of an additional chamber formed by a vessel 7 housing floating piston 8. The oil in chamber 5 and cavity 6 is under constant pressure which is maintained by compressed gas filling a sealed cavity 9 which is formed by floating piston 8 and by the walls of vessel 7, with the cavities 6 and 9 of vessel 7 being separated `from each other by lloating piston 8. Vessel 7 serves as a hydraulic compensator whose function is to maintain increased pressure of liquid in working chamber 5 thus compensating for yany changes in volume inside said chamber during operation.

On the forward stroke of Ihammer block 2, chamber 5 increases in volume, and the piston 8 of the accumulator moves towards cavity 6 thus forcing the liquid into said cavity. On the backward stroke of hammer block 2, chamber 5 dcreases in volume, and the liquid is forced therefrom into cavity 6, thus causing piston 8 to move and press the gas in cavity 9.

When the mechanism is off, there is no excess pressure in working chamber 5, and piston 8 is pressed to a saddle 10 by the pressure of gas, with the flow of gas from cavity 9 being arrested. To prevent the leakage of oil from chamber 5 through the clearance between piston 8 and the walls of vessel 7 into cavity 9, the piston 8 carries metal rings 11 with an elastic cup 12 therebetween.

To increase its volume and hence reduce the pressure increase inside, the cavity 9 may be connected through a union 13 to any other vessel provided with compressed gas (not shown in the drawing). The cavity 9 of vessel 7 may carry a spring or any other resilient element instead of gas in order to maintain sufficient pressure to hold piston 8 to the liquid at any changes in the volume of chamber 5 during operation.

The compensator may be not only of a piston-type, but also of other types, e.g. of diaphragm type, wherein the movable piston 8 is replaced by an elastic diaphragm (not shown in the drawing).

If necessary, cavity 9 may be permanently connected to an air-supply system which will feed the compensator constantly. After each blow, hammer block 2 is pressed to a Working tool 14 by the gas pressure in cavity 9 of the compensator.

As shown in FIG. 1, clutch 3 is rigidly fixed to the end of a connecting rod 15 which is set in reciprocal motion along Chamber 5 Aby 'a crank-'andmod mechanism 16 which is driven by electric motor 17 The clutch is a hollow cylinder 18 with a saddle 19 to accommodate a backpressure valve freely sliding on a neck 21.

If the hammer block 2 is limited in stroke in working chamber 5, cylinder 18 may act as a guide for hammer block 2, and the direct stroke thereof is insured by orifices (not shown in the drawing) made in the side wall of cylinder 18. 'Ilhe orifices connect the working chamber 5 to the cavity of cylinder 18 after hammer block 2 is disengaged from clutch 3. When the valve 20 is closed, it will press against the saddle 19 of cylinder 18 and, when open, against ring 22. The clutch 3 is fixed to the end of the connecting rod 15 by nut 23.

To decrease the force which counters the back stroke of hammer block 2, its cross-section should approximately exceed twice that of connecting rod 15.

On moving towards its extreme left position, clutch 3 will slide with its cylinder 18 over head 24 of hammer block 2. Thereupon, sealed chamber 25, the socalled clutching chamber, will be formed between hammer block 2 and cylinder 18 of clutch 3. Clutch 3 sliding over head 24 of hammer block 2 forces the liquid from chamber 25 through orifice 26 and back pressure valve 20 into working chamber 5. Once clutch 3 has reached its extreme left position (cf. the drawing), it will start moving to the right. As soon as it begins to lthus move, the backpressure valve 20 closes, whereupon the liquid pressure of chamber 2S drops below that of chamber 5, or below the gas pressure of cavity 9 of the compensator, and due to which, head 24 of hammer block 2 is acted upon by a force accelerating the left-toright movement of hammer block 2.

Hammer block 2 is thus engaged to clutch 3 by the liquid in chamber 5 being pressed by the gas in cavity 9 of the compensator. This hydro-elastic engagement of clutch 3 with hammer block 2 causes the latter (owing to gas pressure in the compensator) to exactly repeat the movement of clutch 3, provided the minimum liquid pressure in chamber 25 is above 0.

The accelerated left-toright travel of the hammer block, and its subsequent slower travel by inertia in the same direction will continue until channels 27 in the body of hammer block 2, which are closed by sleeve 4 sliding over hammer block 2, again access to chamber 5. The liquid from chamber 5 will then ow through channels 27, thus causing hammer block 2 to displace in relation to clutch 3. After a while, hammer block 2, having left cylinder 18 of clutch 3, will stop under the action of the equivalent pressure of gas in cavity 9, and the hammer block will start gaining speed in the direction of working tool 14 until it strikes the latter.

Clutch 3, having disengaged vfrom hammer block 2 and reached its extreme right position, will resume its leftward progress and the cycle will be repeated as described hereinabove.

The distribution and the cross-section of channels 27 as well as the entrance length of head 24 of hammer block 2 into cylinder 18 of clutch 3 are so designed that head 24 should leave cylinder 18 of clutch 3 when the latter reaches its extreme right position or at some such point. In this case, the blow power will be the maximum possible.

The elements of the mechanism are so designed that the operational air pressure in chamber 25 should always exceed the atmospheric one.

Floating sleeve 4, against which working tool 14 (FIG. 1) rests through reducer coupling 28, also serves to eliminate the backward shock waves.

Between cylinder 18 of the clutch and head 24 of hammer block 2 there will always be a diametral clearance (not shown in the drawing) through which, when accelerating the rightward movement of the hammer block, the liquid will pass from chamber 5 into chamber 25. This clearance decreases the required passage section of channels 27 as regards the given entrance length of head 24 of hammer block 2 into cylinder 18.

Channels 27 may be substituted either by the clearance of required section, by gauged orifices (not shown in the drawing) in head 24 of hammer block 2, or, in backpressure valve 20, which orifices would maintain a constant connection between chambers 25 and 5. During operation, the liquid in chamber 5 is heated mainly because of the resistance to the movement of hammer block 2.

For cooling the mechanism, working chamber 5 is connected through pressure valve 29 to a liquid lfeeder of low output (not shown in the drawing), and is also provided With an escape union 30 having tap 31. Thus, the liquid fed into chamber 5 and circulating therein escapes through union 30 before being heated to excess. By means of tap 31, the pressure of the liquid in the working chamber may be controlled.

The crank-and-rod mechanism 16 is covered with casing 32.

A mechanism of percussive action of a somewhat modified design is illustrated in FIG. 2.

Vessel 7 with cavities 6' and 9', which are separated from each other by oating piston 8, is built in body 1 of the mechanism to serve as a hydraulic compensator.

The cavity 9' of the compensator is filled with compressed gas, the pressure of which is constantly transmitted via a floating piston 8 to the liquid filled cavity 6 and the work-ing chamber 5 communicating with the cavity 6 through orifices 33.

This compensator functions in a similar manner to that illustrated in connection with FIGURE 1. The only difference is that the compensator is built in the mechanism and at one side carries clutch 3' and while at the other side a projection 34 rests against a slanted washer 35 mounted on shaft 36 of the electric motor. When rotating sh-aft 36, slanted washer 35 causes the compensator to move to the left (cf. drawing) against the force of liquid pressure from chamber 5.

The mechanism shown in FIG. 2 is sufficiently low in weight and size to be hand-operated, e.g., in jackhammers.

The invention is not limited by the hereinabove described embodiment thereof, as alterations and modifications are possible within the spirit and scope of the present invention, yas specified in the appended claims.

I claim:

1. A mechanism of percussive action, preferably for use in drills, incorporating a body, a pair of the interior of said body serving as a working chamber filled with liquid; a hammer block housed in said body and performing reciprocating motion, part of said hammer block (head) being located in said working chamber; a drive serving to actuate said hammer block on a backward stroke; means for -clutching said hammer block and connecting the latter with said drive on a backward stroke, said means moving in said working chamber; an additional chamber connected to said Working chamber and housing a resilient element, preferably gas, said resilient element serving to maintain constant pressure on the liquid in said working chamber; and a partition separating the liquid from the resilient element and transmitting constant pressure from the resilient element to the liquid in said working chamber, the liquid transmitting kinetic energy to said hammer block and actuating said clutch.

2. The mechanism as claimed in claim 1, wherein part of said hammer block (head) engaged with said clutch, has a larger cross-section than that of the part of the hammer facing the working tool.

3. The mechanism as claimed in claim 2, wherein a means for clutching said hammer block is a cylinder rigidly fixed to the end of said connecting rod, having an inside diameter equal to the diameter of said hammer block head and carrying a back-pressure valve serving to let the liquid through said cylinder, While the hammer block head enters the cylinder cavity, said hammer block moving on back stroke together with the cylinder under thelpressure of the liquid on said head from the working too 4. A mechanism as claimed in claim 1 Whose body carries in front a movable sleeve serving as a guide for the hammer block, closing the Working chamber and absorbing the reflected shock waves.

5. A mechanism as claimed in claim 1, wherein said working chamber is connected to a source of liquid circuiating in said working chamber and escaping from it through a pipe carrying a tap to control liquid pressure inside the chamber.

6. A mechanism of percussive action, preferably for use in drills, incorporating a body, a part of the interior of said body serving as a working chamber lled with liquid; a hammer block housed in said body and performing reciprocating motion, part of said hammer block (head) being located in said Working chamber; a drive provided with a crank-and-rod transmission and connecting rod serving to actuate said hammer block on a backward stroke; a means for clutching said hammer block, said means being fixed to the end of said connecting rod, engaging said hammer block on a backward stroke and moving in said working chamber; an additional chamber connected to said working chamber and housing a resilient element, preferably gas, said resilient element serving to maintain constant pressure on the liquid in said working chamber; and a partition separating the liquid from the resilient element and transmitting constant pressure from the resilient element to the liquid in said working chamber, said liquid transmitting kinetic energy to said hammer block and actuating said clutch.

7. A mechanism as claimed in claim 6, in which the cross-section of the connecting rod is approximately twice less than the cross-section of the part of the hammer block facing the working tool.

8. A mechanism of percussive action, preferably for use in drills, incorporating a body, a part of the interior of said body serving as a working chamber filled with liquid; an additional chamber connected to said working chamber and housing a resilient element, preferably gas, said resilient element serving to maintain constant pressure on the liquid in said working chamber; a partition separating the liquid from the resilient element and transmitting constant pressure from the resilient element to the liquid in said working chamber; a hammer block housed in said body and performing reciprocating motion, part of said hammer block (head) being located in said working chamber and having a cross-section larger than that of the part of the hammer block facing the Working tool; a drive provided with a crank transmission and connecting rod to actuate said hammer block on a back stroke; a cylinder rigidly fixed to the end of said connecting rod, having an inside diameter equal to the diameter of the hammer block head and carrying a back-pressure valve serving to let the liquid through said cylinder while the hammer block head enters said cylinder, said hammer block head moving on a back stroke together with said cylinder under the pressure of liquid on said head from the working tool; and said hammer block having channels in its body which, on a full back stroke of the hammer block, connect the cavity of said cylinder with .Said Working chamber thus providing the disengagement of said hammer block from said cylinder.

9. A mechanism of percussive action, preferably for use in drills, incorporating a body, a part of the interior of said body serving as a working chamber lled with liquid; a hammer block housed in said body and performing reciprocating motion, part of said hammer block (head) being located in said working chamber; a drive actuating said hammer block on a back stroke; a means for clutching said hammer block and connecting the latter with said drive on a back stroke, said means moving in said working chamber; a vessel connected to said working chamber and housing a resilient element, preferably gas, said resilient element serving to maintain constant pressure on the liquid in said Working chamber; and a piston located in said vessel and separating the liquid from the resilient element, said piston transmitting constant pressure from the resilient element on the liquid in said chamber, said liquid transmitting kinetic energy to said hammer block and actuating said clutch.

10. The mechanism as claimed in claim 9, in which said vessel for housing said resilient element is located outside the body.

11. The mechanism as claimed in claim 9, in which said vessel for housing said resilient element is located inside the body.

12. The mechanism as claimed in claim 11 in which said vessel with resilient elements is defined by a movable cylinder rigidly connected to said clutching means and periodically coacts with said drive by a cam transmission.

13. A mechanism of percussive action, preferably for use in drills, incorporating a body, a part of the interior of said body serving as a working chamber filled with liquid; a hammer block housed in said body and performing reciprocating motion, part of said hammer block (head) being located in said working chamber; a drive provided with a cam transmission actuating said hammer block on a back stroke; a means for clutching said hammer block and connecting the latter -with said drive on back stroke, said means moving in said working chamber; a vessel housed in said body, said vessel being connected to said workin-g chamber and housing a resilient element,

preferably gas, said resilient element serving t0 `maintain 10 constant pressure on the liquid in said working chamber; and a piston located in said vessel and separating the liquid from the resilient element, said piston transmitting constant pressure from the resilient element to the liquid 1,829,609 10/1931 Robinson 173-116 1,901,779 3/1933 Skeel et al. 173--116 1,921,628 8/1933 Maxwell et al 173--116 2,776,539

FRED C. MATTERN, JR., Primary Examiner.

L. P. KESSLER, Assistant Examiner.

l/l957 Pearson 173-123'y 

1. A MECHANISM OF PERCUSSIVE ACTION, PREFERABLY FOR USE IN DRILLS, INCORPORATING A BODY, A PAIR OF THE INTERIOR OF SAID BODY SERVING AS A WORKING CHAMBER FILLED WITH LIQUID; A HAMMER BLOCK HOUSED IN SAID BODY AND PERFORMING RECIPROCATING MOTION, PART OF SAID HAMMER BLOCK (HEAD) BEING LOCATED IN SAID WORKING CHAMBER; A DRIVE SERVING TO ACTUATE SAID HAMMER BLOCK ON A BACKWARD STROKE; MEANS FOR CLUTCHING SAID HAMMER BLOCK AND CONNECTING THE LATTER WITH SAID DRIVE ON A BACKWARD STROKE, SAID MEANS MOVING IN SAID WORKING CHAMBER; AN ADDITIONAL CHAMBER CONNECTED TO SAID WORKING CHAMBER AND HOUSING A RESILIENT ELEMENT; PREFERABLY GAS, SAID RESILIENT ELEMENT SERVING TO MAINTAIN CONSTANT PRESSURE ON THE LIQUID IN SAID WORKING CHAMBER; AND A PARTITION SEPARATING THE LIQUID FROM THE RESILIENT ELEMENT AND TRANSMITTING CONSTANT PRESSURE FROM THE RESILIENT TO THE LIQUID IN SAID WORKING CHAMBER, THE LIQUID TRANSMITTING KINETIC ENERGY TO SAID HAMMER BLOCK AND ACTUATING SAID CLUTCH. 